There has long been a need for the preservation of citrus juices, and many methods and additives have been used. Citrus juices are known to develop a brown or dark color in a relatively short period of time when exposed to air, due at least in part to oxidative changes. However, browning of citrus juices can also occur in the absence of air. The browning in citrus juices, and lemon juice in particular, is a complicated reaction that is both enzymatic, non-enzymatic, aerobic, anaerobic and is influenced by temperature, oxygen, amino acids, metal catalysts, pH, ascorbic acid content and sugar concentrations. Previous efforts to reduce or eliminate browning include ascorbic acid addition, addition of sulfiting agents, such as sulfur dioxide, and exposure to stannous ions, either from packaging in containers with exposed tin surfaces, or by the addition to the juice of a source of stannous ions. Ascorbic acid addition alone is not always effective and can even promote rather than retard browning in concentrated lemon juice. Addition of ascorbic acid-2-phosphate esters and ascorbyl-6-fatty acid esters is also known.
Sulfites, such as sodium bisulfite, have recently been the subject of scrutiny by health officials, and may be the cause of allergic-type reaction by people eating foods treated with sulfites. Asthmatic sufferers are known to exhibit anaphylactic shock upon exposure to sulfites.
Therefore, a need exists for a method to preserve for several months citrus juices, such as lemon juice, without refrigeration or use of sulfites.